Pneumatic compressor recirculation valve system for minimizing surge under boost during throttle closing

ABSTRACT

An engine system having a compressor coupled to an engine and supplying air to an intake manifold, a throttle controlling the supply of air from the compressor to the intake manifold, a vacuum reservoir, an aspirator having its motive section in fluid communication with the air intake system upstream of the compressor and its discharge section in fluid communication downstream of the compressor and a suction port in fluid communication with the vacuum reservoir, a compressor recirculation valve having a pneumatic control chamber in fluid communication with downstream air from the compressor and in fluid communication with the vacuum reservoir, a gate valve controlling the fluid communication of the pneumatic control chamber of the compressor recirculation valve with the downstream air and the vacuum reservoir, and a bleed line having a bleed valve in fluid communication with the vacuum reservoir and the pneumatic control chamber of the compressor recirculation valve.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/834,539, filed Jun. 13, 2013, which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

This application relates to compressor recirculation valves (“CRV”),more particularly to such valves in a system to control therecirculation of turbocharger compressor outlet air around thecompressor and back to the compressor inlet in order to minimize surge.

BACKGROUND

The advent of affordable natural gas has been embraced by the makers ofover the road vehicle engines and they are now adapting their formerlydiesel fueled engines to operate with natural gas. This requires somechanges, including the addition of a throttle in the intake air stream.When the throttle is closed quickly a condition call surge can beinitiated. When a turbocharger is in a state of surge it no longer caneffectively compress the intake charge, however it is still absorbingpower from the exhaust gas flow. In a throttle closing transient thisloss of compression causes the turbocharger to speed up, whilesimultaneously the flow rate of air into the engine is decreased. In afraction of a second the exhaust power available to the turbochargerdecreases dramatically, slowing the turbocharger back down and in turnincreasing the compression pressure.

This unstable operation can occur for several oscillations, causing thevehicle to vibrate and the torque output by the engine to vary. Thus,there is a need for improved designs to control the turbochargeroperation during the transient throttle closing period in a natural gaspowered engine.

SUMMARY

In one aspect, an engine system is disclosed that minimizes surge duringboost without an external control system monitoring and activating a CRVand a gate valve, the two valves operate purely on the changes inpressure within the system, thereby forming a loop that resets itself.This engine system includes a compressor coupled to an engine andsupplying air to an intake manifold, a throttle controlling the supplyof air from the compressor to the intake manifold, a vacuum reservoir,an aspirator having its motive section in fluid communication downstreamof the compressor and its discharge section in fluid communicationupstream of the compressor, wherein a suction port of the aspirator isin fluid communication with the vacuum reservoir, a compressorrecirculation valve having a pneumatic control chamber in fluidcommunication with downstream air from the compressor and in fluidcommunication with the vacuum reservoir, a gate valve controlling thefluid communication of the pneumatic control chamber of the compressorrecirculation valve with the downstream air and the vacuum reservoir,and a bleed line having a bleed valve in fluid communication with thevacuum reservoir and the pneumatic control chamber of the compressorrecirculation valve.

The engine system under boost with the throttle open operates asfollows: the aspirator evacuates the vacuum reservoir and the gate valvemoves to a first open position placing the pneumatic control chamber ofthe compressor recirculation bypass valve in fluid communication withthe downstream air from the compressor thereby closing the compressorrecirculation valve. Then when the throttle closes, the gate valveswitches from the first open position to a second open position placingthe pneumatic control chamber of the compressor recirculation bypassvalve in fluid communication with the vacuum reservoir thereby openingthe compressor recirculation valve in response to a vacuum reservoirpressure. In the second open position the vacuum reservoir is in fluidcommunication with the bleed line and fluid is drawn through the bleedvalve thereby dissipating the vacuum reservoir pressure, which enablesthe compressor recirculation valve to return to a closed position.

In another aspect, a method for automatically minimizing surge duringboost in an engine system is disclosed that implements the engine systemdescribed herein. The method includes providing such an engine systemand operating the engine under a boost condition, which causes theaspirator to evacuate the vacuum reservoir and the gate valve to move toa first open position placing the pneumatic control chamber of thecompressor recirculation bypass valve in fluid communication with thedownstream air from the compressor thereby closing the compressorrecirculation valve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a system configuration thatincludes a pressure boost sensing compressor recirculation valve (CRV).

FIG. 2 is a cross-sectional view of a snap actuator gate valve takentransverse to the longitudinal axis of the conduit through the gatemember, with the valve in a first open position aligned with a firstconduit.

FIG. 3 is a cross-sectional view of the snap actuator gate valve of FIG.2 with the valve in a second open position aligned with a secondconduit.

DETAILED DESCRIPTION

The following detailed description will illustrate the generalprinciples of the invention, examples of which are additionallyillustrated in the accompanying drawings. In the drawings, likereference numbers indicate identical or functionally similar elements.

As used herein “fluid” means any liquid, suspension, colloid, gas,plasma, or combinations thereof.

FIG. 1 illustrates at least a portion of an engine system, generallydesignated as reference number 10, for example, a natural gas enginesystem, having a CRV 12 controlled by a unique assembly of componentswithin an engine system. The engine system includes a compressor 20 influid communication with an engine manifold 22 and having a throttlecontrol 24 disposed in the fluid stream between the manifold 22 and thecompressor 20. In embodiments where the boosting device is aturbocharger, compressor 20 may be coupled to, and driven by a turbine(not shown) in the engine exhaust of the engine system 10. The assemblyoperating the CRV 12 includes an aspirator 14, a vacuum reservoir 16, avacuum limiting valve 18, and a gate valve 19 controlling fluidcommunication between the compressor 20 and the CRV 12 and between thevacuum reservoir 16 and the CRV 12 and a bleed line 52 that ties intothe system upstream of the compressor 20. The system 10 includes aconduit 36 connecting a control chamber within the gate valve 19 to thefluid stream proximate the manifold 22 in a position between themanifold 22 and the throttle control 24. This can be described as beingconnected in fluid communication with the manifold 22 downstream of thethrottle 24. The system 10 may also include one or more valves such as,but not limited to, check valves 30, 32. Conduit is not to be construedto mean any specific type of material or connection and should beunderstood to include tubing, hoses, pipes, and the like whether rigidor flexible.

The aspirator 14 is one that generates vacuum pressure and is connectedin fluid communication between a first end 26 and a second end 28 of acompressor 20 in such a way that when the compressor 20 is generatingboost the aspirator 14 is generating vacuum. As seen in FIG. 1, theaspirator 14 is connected in fluid communication downstream of thesecond end 28 of the compressor 20 such that the compressed air exitingthe compressor provides the motive flow M into the aspirator 14 viaconduit 56 and the discharge flow D is discharged upstream of the firstend 26 of the compressor 20 via conduit 54. The aspirator 14 may be, butis not limited to, the configurations disclosed in commonly assignedU.S. patent application Ser. No. 14/294,727, filed Jun. 3, 2014, hereinincorporated by reference in its entirety. The suction port 15 of theaspirator 14 is in fluid communication with the vacuum reservoir 16 andmay include a first check valve 30 in the fluid stream therebetween tocontrol the evacuation of the vacuum reservoir 16 as a result of themotive flow through the aspirator 14. The vacuum reservoir 16 includes avacuum limiting valve 18 to limit the amount of reservoir vacuumpressure generated and is connected to the gate valve 19, in particularto its second inlet port 40 by a conduit 60.

The CRV 12 has a pneumatic control chamber and a spring (not shown) in aconfiguration similar to that in FIGS. 2 and 3, but may include a gatevalve, a poppet valve, a butterfly valve, or other known valveconstructions to open and close the bypass 66. In FIG. 1, the CRV 12includes an inlet port 62 and an outlet port 64 in fluid communicationwith one another when the valve portion of the CRV 12 is in an openposition, which allows compressed air to flow through the bypass 66 backto the upstream side of the compressor 20. The movement of the valveportion of the CRV 12 is controlled by the spring and pressuresintroduced or removed from the pneumatic control chamber. The controlport 13 of the pneumatic control chamber is in fluid communication withdownstream air from the compressor and in fluid communication with thevacuum reservoir 16. However, these two are controlled by the gate valve19.

The gate valve 19 includes a pneumatic control chamber 103 (see FIGS. 2and 3) having a control port 42 (FIG. 1) connected to intake manifoldpressure downstream of the throttle by conduit 36. Conduit 36 may bereferred to as a pressure “sensing” line because when the pressuredecreases in conduit 36, in particular once the throttle closes, thedecrease in pressure is “sensed” and automatically the gate valve 19switches from a first open position 140 (FIG. 2) to a second openposition 142 (FIG. 3).

Referring again to FIG. 1, the gate portion 19′ of the gate valve 19includes a first inlet port 46 extending therefrom and a first outletport 48 extending therefrom in opposite directions and aligned for fluidcommunication with one another. The fluid communication therebetween iscontrolled by the gate valve 19. The gate valve 19 includes a gatemechanism movable to allow fluid to flow from the first inlet port 46 tothe second outlet port 48. This may include aligning a passageway 129 inFIG. 2 in the gate mechanism with the first inlet port 46 or moving thegate mechanism such that it does not block or obstruct the first inletport 46. The gate portion 19′ also includes a second inlet port 40extending therefrom and a second outlet port 50 extending therefrom inopposite directions and aligned for fluid communication with oneanother. The fluid communication therebetween is controlled by the gatevalve 19 in a similar manner to that just described for the first inletport 46.

Gate valve 19 also includes a closing mechanism or actuator 104 (seeFIGS. 2 and 3) to control the flow of fluid from the first inlet port 46to the first outlet port 48 and from the second inlet port 40 to thesecond outlet port 50. In FIG. 1, the first outlet port 48 is in fluidcommunication with the control port 13 of the pneumatic control chamberof the CRV 12. Thus, when the valve mechanism 120 is in the first openposition 140 depicted in FIG. 2, compressed air is in fluidcommunication with the pneumatic control chamber of the CRV 12. Asdepicted in FIG. 1, the second outlet port 50 is also in fluidcommunication with the control port 13 of the pneumatic control chamberof the CRV 12. Thus, when the valve mechanism 120 is in the second openposition 142 depicted in FIG. 3, the vacuum canister 16 is in fluidcommunication with the control port 13 of the pneumatic control chamberof the CRV 12 and can reduce the pressure in the pneumatic controlchamber. Accordingly, both the first outlet port 48 and the secondoutlet port 50 are connected to control port 13 and hence the pneumaticcontrol chamber of the CRV 12 for fluid communication therewith toaffect the opening and closing of the valve portion thereof.

Referring to FIG. 1, the bleed line 52 with its bleed valve 34 has afirst junction with the fluid stream flowing from the first outlet port48 and the second outlet port 50 of the gate valve 19 to the controlport 13 of the CRV 12 and a second junction with the air inductionsystem 38. The bleed line 52 includes the second check valve 32 disposedbetween the first junction and the bleed valve 34.

Referring now to FIGS. 2 and 3, the gate valve 19, in one embodiment,may be a snap actuator gate valve 100. The snap actuator gate valve 100includes a container portion 130 and a cap 132 sealingly connected tothe container portion 130 and defining an internal chamber 103 andhaving a control port 42 (FIG. 1) in fluid communication with thechamber 103. Housed within the chamber 103 is an actuator 104 thatincludes a piston 110 having a stem 114 connectable to a valve mechanism120. The stem 114 has a proximal end 152 (which may be referred toherein as the coupling end) proximate to the valve mechanism 120 and adistal end 154 removed from the valve mechanism 120 (labeled in FIG. 2).The valve mechanism 120, in this embodiment, includes a pocket 126enclosing the gate member 128, which has a passage 129 therethrough. Thepocket 126 is connected to a first conduit 58 by the first inlet port 46and to a second conduit 60 by the second inlet port 40 and opposite thefirst conduit 58 is connected to the control port 13 of the CRV 12 andopposite the second conduit 60 is connected to the bleed line 52 and thecontrol port 13 of the CRV 12.

Still referring to FIGS. 2-3, the gate member 128 is connected to thepiston 110 by a rail system 160 providing sliding movement of the gatemember 128 in the direction of and in response to fluid flow therebyforming a seal against the pocket 126. The rail system 160 includes aguide rail 162 near the proximal end 152 of stem 114. The guide rail 162includes raceway grooves 164 on opposing sides thereof. The gate member128 includes a slider 166 shaped and configured to fit over the guiderail 162 and conform to the raceway grooves 164.

The actuator 104 controls the opening and closing of the valve mechanism120, in particular the gate member 128 by the movement of the piston110. As seen in FIGS. 2 and 3, the piston 110 is movable between a firstopen position 140 (FIG. 2) where the gate is aligned with the firstconduit 58 and a second open position 142 (FIG. 3) where the gate closesthe first conduit 58 and opens the second conduit 60. The valvemechanism 120 may start in either position or may be elongated, and thefirst and second conduits 58, 60 spaced apart further relative to oneanother, to also provide for a closed position for both the first andthe second conduits 58, 60 at the same time.

The piston 110 at least partially includes a magnetically-attractablematerial 111 (or is made of such material) such that the piston 110 isattractable to a first magnet 116 and a second magnet 118. A spring 112is seated against the piston 110 to bias the piston 110 generally intothe first open position 140 (FIG. 2) and the first magnet 116 ispositioned to assist the spring 112 in maintaining the piston 110 in thefirst open position 140. The second magnet 118 is positioned to maintainthe piston 110 in the second open position 142 (FIG. 3), when the piston110 moves thereto. The piston 110 may also include a sealing member 134about its outer periphery as a lip seal against the interior surface ofchamber 103. The outer periphery of the piston 110 may include anannular groove 136 in which to seat the sealing member 134. In oneembodiment, the sealing member 134 may be an O-ring, a V-ring, or anX-ring. Alternately, the sealing member 134 may be any other annularseal made of sealing material for sealing engagement against anothermember.

The stem 114 of the piston may also extend therefrom opposite the valvemechanism, and, as seen in FIGS. 2-3, be received in a guide channel 146within the cap 132. The cap 132 may also include a seat 148 for thespring 112. These features of the cap 132 provide alignment to theactuator and prevent twisting and/or buckling of the spring and piston.

The actuator 104 may include a first bumper 138 positioned to reducenoise between the piston 110 and the housing 102 when arriving in thestarting position 140 and a second bumper 139 positioned to reduce noisebetween the piston 110 and the housing 102 when arriving in thesecondary position 142. The first bumper 138 may also be positioned toseal the opening 150 between the housing 102 and the valve mechanism 120(see FIGS. 2 and 4). In one embodiment, opening 150 may be defined by agenerally frustoconical surface. The first and second bumpers 138, 139may be seated in annular grooves within the housing 102 or on acomponent of the piston 110, such as the stem 114.

In operation, the actuator 104 moves the piston 110 by the introductionof fluid into or the removal of fluid from the chamber 103 via thecontrol port 42 and by the assistance of the magnets 116, 118 and thespring 112. The piston 110 is seated in the first open position 140(FIG. 2) and remains in this position held there by the spring force andthe magnetic force of the first magnet 116 until a threshold force isapplied to the piston 110 that overcomes the spring force and magneticforce of the first magnet. Once this threshold force is reached, thepiston 110 will move the full length of its travel to its second openposition 142 (FIG. 3) with the assistance of the magnetic force of thesecond magnet, which thereafter maintains the piston 110 in thesecondary position 142. The movement of the piston 110 through its fulllength of travel is a quick, nearly instantaneous movement substantiallywithout pause therebetween, i.e., there is no lag or floating of thepiston between the starting position 140 and the secondary position 142,which may be described as a “snap” movement of the piston. This “snap,”which without bumpers is an audible sound, is a result of the magneticattraction of the second magnet 118 for the piston 110, which acts toquickly move the piston to the second open position 142. The secondmagnet 118 thereafter holds or maintains the piston 110 in the secondopen position 142 until a lower threshold force is reached, at whichpoint the piston moves back to the first open position 140 by againmoving the full length of its travel as a snap-type movement. The snapactuator gate valve 100 may also include other features disclosed incommonly assigned U.S. patent application Ser. No. 14/154,268, filedJan. 1, 2014 and herein incorporated by reference in its entirety.

In operation there are three states to consider: (1) steady state withboost, (2) the throttle closing state, and (3) steady state with noboost. When the engine is under boost the boost pressure causes twothings to occur: (a) the gate valve 19 moves the valve to a positionwhere fluid communication is allowed between the first inlet port 46 andthe first outlet port 48, thereby providing fluid communication betweenthe second end 28 of the compressor 20 and the control port 13 and thepneumatic control chamber of the CRV 12; and (b) the aspirator 14generates vacuum which evacuates the vacuum reservoir 16. Occurrence (a)enables compressor outlet pressure, exiting the compressor 20, to act onthe actuator inside the CRV 12 and thereby move the actuator to a closedvalve position where it remains until this pressure inside the pneumaticcontrol chamber is removed or overcome.

In the throttle closing state (i.e., when throttle 24 is closed), theintake manifold pressure reduces and decreases the pressure in thepressure “sensing” line, conduit 36. This decrease in pressure in turncauses the gate valve 19 to move, switching its fluid communication fromthe first outlet port 48 to the second outlet port 50. The second inletport 40, as mentioned above, is connected to the vacuum reservoir 16 forfluid communication therebetween. This evacuates the pressure from thepneumatic control chamber of the CRV 12, which in turn opens the valveportion of the CRV 12 to short circuit the compressor flow from itssecond end 28 (outlet) back to its first end 26 (inlet) through bypass66. Once the vacuum reservoir 16 is in open fluid communication with theCRV 12 fluid begins to be drawn (flow) through the second check valve 32from the bleed valve 34 and from the air induction system (includingbeing drawn away from the first end 26 (inlet) of the compressor 20),causing the canister vacuum to dissipate and thereby moving the actuatorwith the CRV 12 to a closed position, which shuts the bypass the CRV 12had created.

At state “(3)”, steady state with no boost state, the CRV returns to theclosed position, due to the leakage of air through bleed line 52 fillingthe vacuum reservoir 16. Here, the gate valve 19 remains in the firstsecond open position 142.

The above described engine system automatically minimizes surge duringboost. Here, no external control system is required to monitor andactivate the CRV or the gate valve, they operate purely on the changesin pressure within the system, thereby forming a loop that resetsitself.

Having described the invention in detail and by reference to preferredembodiments thereof, it will be apparent that modifications andvariations are possible without departing from the scope of theinvention which is defined in the appended claims.

What is claimed:
 1. An engine system comprising: a compressor coupled toan engine and supplying air to an intake manifold; a throttlecontrolling the supply of air from the compressor to the intakemanifold; a vacuum reservoir; an aspirator having its motive section influid communication downstream of the compressor and its dischargesection in fluid communication upstream of the compressor, wherein asuction port of the aspirator is in fluid communication with the vacuumreservoir; a compressor recirculation valve having a pneumatic controlchamber in fluid communication with downstream air from the compressorand in fluid communication with the vacuum reservoir; a gate valvecontrolling the fluid communication of the pneumatic control chamber ofthe compressor recirculation valve with the downstream air and thevacuum reservoir; and a bleed line having a bleed valve in fluidcommunication with the vacuum reservoir and the pneumatic controlchamber of the compressor recirculation valve.
 2. The engine system ofclaim 1, wherein the compressor is a portion of a turbocharger coupledto the engine.
 3. The engine system of claim 1, wherein the vacuumreservoir includes a vacuum limiting valve.
 4. The engine system ofclaim 1, further comprising a check valve between the suction port ofthe aspirator and the vacuum reservoir.
 5. The engine system of claim 1,wherein the gate valve includes a pneumatic control chamber in fluidcommunication with air entering the intake manifold upstream of thethrottle.
 6. The engine system of claim 1, further comprising a checkvalve between the bleed valve and the gate valve; wherein the bleed lineis in fluid communication with the air induction system upstream of thecompressor.
 7. The engine system of claim 1, wherein, under boost withthe throttle open, the aspirator evacuates the vacuum reservoir and thegate valve moves to a first open position placing the pneumatic controlchamber of the compressor recirculation bypass valve in fluidcommunication with the downstream air from the compressor therebyclosing the compressor recirculation valve.
 8. The engine system ofclaim 7, wherein, when the throttle closes, the gate valve switches fromthe first open position to a second open position placing the pneumaticcontrol chamber of the compressor recirculation bypass valve in fluidcommunication with the vacuum reservoir thereby opening the compressorrecirculation valve in response to a vacuum reservoir pressure.
 9. Theengine system of claim 8, wherein in the second open position the vacuumreservoir is in fluid communication with the bleed line and fluid isdrawn through the bleed valve thereby dissipating the vacuum reservoirpressure, which enables the compressor recirculation valve to return toa closed position.
 10. The engine system of claim 9, wherein the bleedline is in fluid communication with the air induction system upstream ofthe compressor and fluid is drawn from the first end of the compressorwhile being drawn through the bleed valve.
 11. The engine system ofclaim 1, wherein the engine is a natural gas engine.
 12. A method forautomatically minimizing surge during boost in an engine system, thesystem comprising: providing the engine system of claim 1; operating theengine under a boost condition; wherein the aspirator evacuates thevacuum reservoir and the gate valve moves to a first open positionplacing the pneumatic control chamber of the compressor recirculationbypass valve in fluid communication with the downstream air from thecompressor thereby closing the compressor recirculation valve.
 13. Themethod of claim 12, further comprising closing the throttle; wherein thegate valve switches from the first open position to a second openposition placing the pneumatic control chamber of the compressorrecirculation bypass valve in fluid communication with the vacuumreservoir thereby opening the compressor recirculation valve in responseto a vacuum reservoir pressure.
 14. The method of claim 13, wherein,with the gate valve in the second open position, the vacuum reservoir isin fluid communication with the bleed line and fluid is drawn throughthe bleed valve thereby dissipating the vacuum reservoir pressure, whichenables the compressor recirculation valve to return to a closedposition.
 15. The method of claim 14, wherein the bleed line is in fluidcommunication with the air induction system upstream of the compressorand fluid is drawn from the first end of the compressor simultaneouslywith fluid drawn through the bleed valve.